The present invention relates to alarm-type locking systems particularly adapted for use on vehicles such as bicycles and motorcycles. Vehicles of this type are easy prey for thieves unless they are securely locked to a stationary member, such as a post or stand, when they are not in use. Accordingly, conventional locking arrangements for securing bicycles or motorcycles to a stationary member when they are not in use typically comprise an elongated chain or cable which loops around the frame of the bicycle or motorcycle and the stationary post or stand. The end of the cable or chain is then locked with a padlock of conventional design. These locking devices have not proved entirely successful in preventing thefts. Heavy duty bolt cutters can easily be employed to cut through high tensile steel and cable lock shafts. Accordingly, it is an object of the present invention to provide a locking system which is tamper proof to the extent that tampering by cutting the cable or prying the casing open actuates a self-contained audible alarm system. The effect of this system will be to surprise and frighten the would-be thief and discourage him from completing the theft because of the audio alarm which would attract attention to him. The present invention, therefore, can effectively serve as a deterrent, stopping the thief short of completing the act of confiscating the bicycle or motorcycle.
Security alarm systems of this general type are not new per se. For example, a similar system is shown in U.S. Pat. No. 3,754,224 issued Aug. 21, 1973 to Willhoe R. Roy et al entitled SECURITY ALARM ACTUATING DEVICE. This system is particularly adapted for sensing unauthorized opening of a gate or the like and includes an electrical series loop incorporated into a mechanical structure for locking relatively movable members of a gate. The Roy system is rather complex and comprises a number of interconnected cooperating elements including a coaxial cable 20 secured to a box 14 mounted on one of the gate members 12, a casing 24 housing a switch operating element 28 also secured to the post 12 and a conventional padlock 42 having a shackle 40. The cable 20 passes through an opening in the bottom of the pin 28 and there mechanically secured in place. Two registered openings 36 and 38 and the pin 28 and the frame 24 may be aligned so as to receive the shackle 40 of the padlock 42. The frame includes a fixedly mounted, normally opened single throw switch 44 having an operating member in the form of a plunger 46 and spring biased outwardly so that when it is depressed the open switch contacts will be closed. With the gate closed and the post 10 and 12 juxtaposed, cable 20 is passed around the post 10 and 12 and the rod 28 is inserted in the frame 24 and positioned to receive the shackle 40 of the lock 42. Engagement of the upper end of the rod 28 with the plunger 46 closes the switch 44 thereby presenting a closed circuit to the terminals 52. Now if the lock 42 is removed, or the cable is cut, an open circuit is presented to the terminals 52 which activates the alarm system.